Alginate gum is a natural gum derived from seaweed (a rich natural resource). Alginate gum is a highly effective gelling and thickening agent and has been widely used in the food and pharmaceutical industries as such an agent. A commonly-used alginate gum is sodium alginate, which has a linear long chain structure. Aqueous solutions of sodium alginate at 1 wt. % are normally within viscosity range of from 100-1000 cps, they are colorless and as viscous fluid under room temperature.
However, disadvantages of sodium alginate for toothpaste applications include lack of structural property for a striped toothpaste and the viscosity/price tends not to deliver cost benefit.
Another type of alginate is calcium alginate. Calcium alginate can be formed by the addition of calcium ions (for example as an aqueous solution of CaCl2 but normally together with chelator like EDTA used to slow down the cross-linking) to sodium alginate. Calcium alginate is water-insoluble.
It would be desirable to provide a rheology modifier which has a clear, colourless appearance when in aqueous solution, yet which still continually flows under an applied shear stress and viscosity, and which provides excellent thickening and structural effects.